Lamp with support for filament to extend life of filament and envelope filled with krypton and/or xenon

ABSTRACT

The specification discloses a lighting system which uses a low voltage lamp filament of a certain increased length to which a predetermined reduced voltage is applied, which is less than the rated voltage of the lamp. The lamp filaments are each supported at their ends on rods and a rod having an insulating grommet is supported between each pair of rods which support the ends of the filament to support the intermediate part of the filament. Thus the center rod support acts on the filament as a support for two parts of a cantilever beam.

United States Patent Spiteri [54] LAMP WITH SUPPORT FOR F ILAMENT T OEXTEND LIFE OF FILAMENT AND ENVELOPE FILLED WITH KRYPTON AND/OR XENON[72] Inventor: Joseph Splteri, Erie, Pa.

[73] Assignee: Truck-Lite Company, Inc., Jamestown, NY

[22] Filed: May 14, 1970 [21] Appl.No.: 37,183

Related 0.8. Application Data [63] lCgginuation-in-part of Ser. No.785,909, Dec. 23,

521 u.s.c| ..315/64,315/66,3l5/200, 315/241, 315/273 51 1m.c|..I-I0lj7/44 5s FieldofSearch ..3l5/64,66,200,20l,205, 315/241, 272,273, 65, 67, 68

[ 56] References Cited UNITED STATES PATENTS 3,416,028 12/1968 Levin..315/64 X [451 Apr. 4, 1972 3,275,922 9/1966 Meyer et al. 1 5/200 X2,306,559 12/1942 Pearson ..315/66 3,075,123 l/l963 Faulds ....3l5/200 X3,215,891 11/1965 Fritz et al... ....315/200 X 2,082,326 l/l937 Dulberg..315/66 2,896,125 7/1959 Morton ....3 1 5/200 X 2,981,866 4/1961 Tsienet a1. ..315/200 FOREIGN PATENTS OR APPLICATIONS 398,693 9/1933 GreatBritain ..3 15/64 Primary ExaminerEli Lieberman AssistantExaminer-Saxfield Chatmon, Jr. Attorney-Charles L. Lovercheck [5 7]ABSTRACT The specification discloses a lighting system which uses a lowvoltage lamp filament of a certain increased length to which apredetermined reduced voltage is applied, which is less than the ratedvoltage of the lamp. The lamp filaments are each supported at their endson rods and a rod having an insulating grommet is supported between eachpair of rods which support the ends of the filament to support theintermediate part of the filament. Thus the center rod support acts onthe filament as a support for two parts of a cantilever beam.

1 Claim, 9 Drawing Figures LAMP WITH SUPPORT FOR FILAMENT TO EXTEND LIFEOF FILAMENT AND ENVELOPE FILLED WITH KRYPT ON AND/OR XENON REFERENCE TOCO-PENDING APPLICATION This application is a continuation-in-part ofpatent application, Ser. No. 785,909, filed Dec. 23, 1968.

STATEMENT OF INVENTION This invention relates to lighting systems of theincandescent filament type and, more particularly, to lamps and the lifeof such lighting systems.

OBJECTS OF THE INVENTION It is an object of the invention to provide animproved filament support in an incandescent lamp.

Another object of the invention is to provide a filament support whichwill increase the life of the lamp.

Another object of the invention is to provide a filament support at aplurality of points.

Another object of the invention is to provide a lamp that will have alonger life with comparable candlepower output than an ordinary lamp ofthe same power consumption.

Another object of the invention is to provide a lamp wherein the lampwill operate at a lower temperature with comparable candlepower outputthan the ordinary lamp.

Another object of the invention is to provide a more rugged filament andfilament support for a lamp adapted to be used in the automotive/truckindustry.

Another object of the invention is to provide a lamp that offers areduction in power consumption with comparable candlepower to a lamp ofsimilar output.

Another object of the invention is to provide a lamp that is moreeconomical to operate and more reliable than a lamp of comparable powerconsumption and light output.

DESCRIPTION OF THE DRAWINGS FIG. 1 shows a side elevational view of anincandescent lamp constructed in accordance with the present inventionwith parts broken away and shown in section.

FIG. 2 is a transverse sectional view taken substantially through aplane indicated by section line 22 of FIG. 1.

FIG. 3 is an enlarged detail view showing a portion of the filamentassembly associated with the lamp of the present invention.

FIG. 4 is a simplified circuit diagram of a voltage reducing circuitassociated with the invention.

FIG. 5 shows an enlarged partial view of the support taken at line 55ofFlG. 2.

FIG. 6 shows the vibration pattern of a filament supported only at itsends.

FIG. 7 shows a filament supported at an intermediate point.

FIG. 8 shows the vibration pattern of a filament supported at twointermediate points.

FIG. 9 shows the vibration pattern of a filament support.

DETAILED DESCRIPTION OF THE DRAWINGS Now with more particular referenceto the drawings, FIGS. 1 and 2 illustrate a typical incandescent lampconstructed in accordance with the present invention, generally referredto by a reference numeral 10. As in the case of most incandescent typesof lamps, the lamp 10 includes an outer glass envelope 12 having anenlarged end chamber portion 14 within which a tungsten filamentassembly 16 is mounted in spaced relation to the envelope base 18 towhich the externally threaded connector 20 is secured by thenonconductive bonding material 22. A plurality of support rods 24 areembedded in the internal projection 26 of the base 18 for mounting thefilament assembly 16 within the illumination chamber portion 14.Further, the envelope may be internally coated with a silica coating andfilled with Krypton and/or Xenon gas after being evacuated.

As more clearly seen in FIGS. 2 and 3, the filament assembly includes aplurality of tungsten filaments 28 electrically interconnected in seriesand supported at their-junctures 30 by the upper ends 32 of the supportrods 24. In the illustrated embodiment, five standard tungsten filamentsare shown. The terminal ends 30 of the series connected filaments areconnected to the support rods 24, constituting electrical conductorsconnecting the terminal ends of the filaments to the threaded connector20 at 42 as shown in FIG. 1 and to a conductive terminal element 44mounted on the nonconductive end closure 46. The voltage rating of thefilaments, the number of such filaments and the voltage applied to thefilaments is selected in accordance with certain critical parameters.

The rods 24 are supported between rods 24 on projection 26. The upperends of rods 24' have eyelets 60 formed in them, which receive the wiremaking up rod 24. Three rods 28 may be provided as shown. The rod 24supports the filament 28 at its intermediate part and prevents vibrationof the filament between its ends.

The envelope may be filled with Krypton and/or Xenon gas which will havea tendency to inhibit oxidation of the filament.

FIG. 4 illustrates a typical voltage reducing circuit that may beutilized in order to control the reduced voltage applied to the seriesconnected filaments in accordance with the present invention. Othervoltage reducing circuit arrangements for this same purpose aredisclosed in prior co-pending application, U.S. Ser. No. 676,799entitled Incandescent Lamp Circuit," which was filed on Oct. 20, 1967.

FIG. 5 is a partial enlarged view of part of FIG. 3.

FIG. 6 is a schematic diagram of a filament supported by a centersupport.

FIG. 7 is a schematic view of a filament supported by two outsidesupports and an intermediate support.

FIG. 8 is a schematic view of a filament supported by two outsidesupports and two intermediate supports according to the invention.

In the embodiment of the invention shown in FIG. 9, a schematic view ofa incandescent lamp is shown wherein the supports 124 support thefilament made up of the filament elements 160 and 161. The supports 124will be supported in a base similar to the manner in which the supports24 are supported in the embodiment of FIG. 1. The elements 124 will beconnected to terminals so that a voltage of say volts can be connectedto the filament and a voltage of 12 volts can be connected to theterminals connected to filament 161.

The foregoing specification sets forth the invention in its preferredpractical forms but the structure shown is capable of modificationwithin a range of equivalents without departing from the invention whichis to be understood is broadly novel as is commensurate with theappended claim.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. In combination with a source of voltage of predetermined valueadapted to be directly applied to a standard lamp filament producingillumination of a predetermined lumen output at rated voltage,

a long life lamp assembly comprising filament means having an equivalentlength and diameter corresponding to a plurality of said standard lampfilaments enclosed in a single enclosing element, each supported at bothof its ends and at an intermediate point and connected in series,

and voltage reducing means connecting said filament means to the sourceof voltage for applying a reduced voltage less than rated voltage,

the number of said lamp filaments and the reduced voltage beingsufficient to produce a total illumination at least equal to saidpredetermined lumen output whereby the life of said filament means is anexponential function of the ratio of the rated voltage to the reducedvoltage,

said voltage reducing means comprising a diode connected in series withsaid filament means across the voltage source, and a capacitor connectedin parallel with the filament means.

1. In combination with a source of voltage of predetermined valueadapted to be directly applied to a standard lamp filament producingillumination of a predetermined lumen output at rated voltage, a longlife lamp assembly comprising filament means having an equivalent lengthand diameter corresponding to a plurality of said standard lampfilaments enclosed in a single enclosing element, each supported at bothof its ends and at an intermediate point and connected in series, andvoltage reducing means connecting said filament means to the source ofvoltage for applying a reduced voltage less than rated voltage, thenumber of said lamp filaments and the reduced voltage being sufficientto produce a total illumination at least equal to said predeterminedlumen output whereby the life of said filament means is an exponentialfunction of the ratio of the rated voltage to the reduced voltage, saidvoltage reducing means comprising a diode connected in series with saidfilament means across the voltage source, and a capacitor connected inparallel with the filament means.